1. Field of the Invention
Our invention is an electric switch that selects data by moving contacts along tracks of electrodes such as a rotary type switch having a switch rotor mounted to or with respect to a printed circuit board.
2. Prior Art
Many data switches in this field are known. One example, disclosed in the Japanese Published Examined Utility Model Application No. 53-49308 and shown in FIG. 3, is rotated to a data selection position, and selects the data at that position when a read button (not shown) is pressed. This switch has a contact base 55 with several contacts 55a-55g. The contacts 55a-55g are arranged to correspond to concentric annular electrodes 52a-52g printed on a printed circuit board 51. Each of the electrodes 52a-52g has terminals 53 that can be touched by one of the contacts 55a-55g. The terminals 53 for each electrode 52a-52g are connected by narrower leads 54 that the contacts 55a-55g cannot touch. The contacts 55a-55g slide in unison over the electrodes 52a-55g when the switch is rotated. The contacts 55a-55g are electrically interconnected.
In FIG. 3, the contacts 55a-55g rest on the printed circuit board 51 at the hatched squares. In this example, four contacts 55a, 55c, 55e and 55f touch four electrodes 52a, 52c, 52e and 52f, respectively, thus conducting signal current. Three contacts 55b, 55d and 55g do not touch any of electrodes 52a-52g, and thus conduct no signal current. As a result, the switch, at this position, would read "0110101", where the innermost electrode 52a represents the least significant bit.
In this arrangement, the electrodes 52a-52g are so narrow that attempts to miniaturize the switch leave little margin for error. The contacts 55a-55g have to be made so small that the manufacturing process becomes very complex and expensive, while the strength of the contacts 55a-55g declines allowing greater deterioration during use.